What does the symbol %s mean in Python?

The %s symbol in Python is used for string formatting, specifically for interpolating values into a string using the % operator. It indicates the position where the string representation (of any data type, converted using str()) of the corresponding element from a tuple or dictionary will be inserted.

Here are examples of its usage:

# With one value
name = "Alice"
greeting = "Hello, %s!" % name  # Inserts the value of the variable name as a string
print(greeting)

# With multiple values (using a tuple)
age = 30
message = "My name is %s and I am %s years old." % (name, age) # Values from the tuple are inserted in order
print(message)

# Using a dictionary (for named parameters)
data = {'city': 'Moscow', 'temperature': 25}
weather_report = "In the city %(city)s, it is currently %(temperature)s degrees." % data # Dictionary keys correspond to named parameters
print(weather_report)

Although %s is still used, modern Python prefers string formatting methods .format() and f-strings (starting from Python 3.6) due to their better readability, flexibility, and performance.

Here is a comparison:

Formatting Method	Example	Remarks
% operator	"My name is %s" % name	Older method, less readable for complex cases.
.format() method	"My name is {}".format(name)	More flexible, supports positional and named arguments.
f-strings	f"My name is {name}"	The most modern and readable, often the fastest.